ABSTRACT As of December of 2018, Michigan residents over 21 may legally grow, possess and use Cannabis in their residence. Recreational Cannabis retailers are expected to be available by the end of 2019. Although researchers recognize the importance of understanding the effects of policy change around Cannabis use, there are few studies detailing changes in individual behavior as a result of the policy shift that also accounts for individuals' history with Cannabis use and the multi-level influences that may increase or decrease the probability of use. Moreover, children of drug using parents are already at greater risk for substance use than children of non-drug using parents; such risk is likely to increase in states permitting recreational Cannabis use. The purpose of this study is to understand how the intergenerational transmission of the substance use is affected by Cannabis legalization in an at risk sample of urban young adults and their children. The Flint Youth Injury Study (?FYI?; DA024646) is a predominantly African American longitudinal cohort followed since 2009. The original aims of the FYI study were to study youth drug use and health services utilization over time (N = 599; ages 14-24). We propose to expand the scope of the original FYI study by focusing on 350 of the FYI participants who are now parents (Generation 1 or ?G1?; ages 23-32) and including their children (Generation 2 or ?G2?; 506 children ages 5-14). We will apply a socio-ecological developmental framework to examine the effects of Cannabis legalization on both G1 and G2 Cannabis use, its antecedents and other correlates. Under this time sensitive mechanism, this study will a) assess current Cannabis use in the adult population and link these observations to a rich, 7-wave geocoded G1 dataset; b) document baseline Cannabis-related attitudes, behaviors, parenting practices, and contextual antecedents (e.g., Cannabis dispensaries, community violence) that can influence child Cannabis usage; and c) engage a subsample of families in interviews to understand how legalization affects attitudes and perceived risk, family dynamics related to Cannabis, and contextual influences that may influence current or future use. The proposed study provides a unique and timely opportunity to define Cannabis risk in in the context of a policy transition by addressing the following Specific Aims: Aim 1: Establish a parent/child dyad database from an NIH-funded longitudinal cohort to be used for a larger longitudinal study of the effects of the new Cannabis policy on intergenerational influences. AIM 2: Examine how individual risk and protective factors measured across adolescence and young adulthood predict G1's current Cannabis use, attitudes toward Cannabis and perceptions of risk, and parenting behaviors associated with Cannabis risk in children. AIM 3: Identify which G1 parenting attitudes and behaviors predict G2 Cannabis use antecedents (both risk and promotive factors) and usage. AIM 4: Conduct quarterly interviews with a subsample of G1/G2 dyads to understand evolving Cannabis-related attitudes, knowledge and behaviors as the law is fully implemented.